2.2.1. Intro to Imaging

Question 1

What determines radiographic opacity?

Answer 1

• Material
• Density
• Thickness

Question 2

What material appears BLACK on a radiograph?

What is this characteristic called?

Answer 2

AIR appears black b/c there’s no object to “cast a shadow”

Black areas are where the Xrays shine through = “lucent”

Question 3

What is the term for a material that appears WHITE on a radiograph?

Answer 3

“Radioopaque” - this is when objects “cast a shadow”

Question 4

Arrange in order from most lucent to most radioopaque:

titanium screw, adipose, bone, lung, soft tissue, muscle

Answer 4

(most lucent) lung - adipose - muscle - soft tissue - bone - titanium screw (most radioopaque)

Question 5

Can you determine an object’s shape from a single radiograph?

If not, what’s the minimum you need?

Answer 5

NO!

You need two to determine shape (more can be a waste and cause unnecessary radiation exposure)

Question 6

Name and describe the orientation of the three imaging planes.

Answer 6

• Sagittal = cuts the body longitudinally
• Coronal = cuts the body front-to-back
• Transverse = cuts the body parallel to the floor view

Question 7

Order the steps of generating a radiographic image:

A. Electrons hit a tungsten target & are reflected off

B. Electrons are “boiled off” of the filament

C. Remaining electrons hit a film/sensor

D. Object of interest blocks electrons

E. A tungsten filament is heated

Answer 7

E, B, A, D, C

1. A tungsten filament is heated
2. Electrons are “boiled off” of the filament
3. Electrons hit a tungsten target & are reflected off
4. Object of interest blocks electrons
5. Remaining electrons hit a film/sensor

Question 8

Describe the basic concept of contrast radiography

Answer 8

Technique using a “contrast” (aka dye) to bring out the details in a radiographic image by giving contrast to a structure in question.

Question 9

What does the term “echogenicity” refer to?

Answer 9

This term describes how a tissue/object/etc appears when examined via Ultrasound

• Hyperechoic = bright
• Hypoechoic = dim
• Echogenic = any tissue
• Anechoic = fluid, air

Question 10

What is the specific term for image “density” in a CT scan?

Answer 10

“Attenuation”

Question 11

What does a HIGH attenuation look like on CT scan?

LOW attenuation?

Answer 11

High = white

Low = black

Question 12

List four advantages of CT scanning

Answer 12

1. Rapid
2. Low cost
3. Readily available
4. Great resolution (~1500x greater than XRay)

Question 13

List four disadvantages of CT scanning

Answer 13

1. Patient’s pathology may change from the time the scan was taken
2. Volume averaging
3. Radiation risk from multiple scans
4. Equipment is expensive to procure

Question 14

List four advantages of MRI scanning

Answer 14

1. No radiation
2. Rapid
3. Low cost
4. Generally available

Question 15

List four disadvantages of MRI scanning

Answer 15

1. Changing Pathology
2. Potential for claustrophobia
3. Metal in/on patient
4. Magnetic Field and Radio Frequency cause interference and create inaccurate images

Question 16

How are bright structures described in relation to MRI scans? Dark structures?

Answer 16

Bright = hyperintense

Dark = hypointense

Question 17

Of the T1 and T2 MRI modalities, which makes fat appear white, and which makes water appear white?

Answer 17

T1 = fat

T2 = water (think T2 = H₂O)

Question 18

What is Arterial Spin Labeling (ASL)?

Answer 18

MR Angiography that can be done without the use of a contrast

Question 19

List two advantages to vascular contrast studies (aka angiography)

Answer 19

1. Examines all vessels to find defects
2. Great contrast provided downstream of contrast injection

Question 20

List two disadvantages to performing angiography

Answer 20

1. Can be invasive
2. Exposes patient and staff to increased background radiation (via radioactive tracers)

Question 21

Which is a better term to use around patients and their families, and why?

“Contrast” or “dye”

Answer 21

“Contrast”

• sounds professional, yet simple
• avoids reminding the Pt about death/dying